Most electronic products are composed of circuit modules. With the increasing specialization in designing and manufacturing, the circuit modules contained in a single electronic product may be designed or manufactured by different companies. For example, a cell phone generally includes a plurality of circuit blocks, e.g. an RF/IF (radio frequency/intermediate frequency) module 11, a baseband/control module 12, a memory module 13, an input key module 14, an audio module 15 and a display module 16, as shown in FIG. 1. For manufacturing such a cell phone, the maker purchases necessary parts and devices from various suppliers, and properly combines these parts and devices to assemble the cell phone. Among the devices, the baseband/control module 12 includes a core device, e.g. an SOC (system on chip) 120, which is generally purchased from an IC design company and further modified by the cell phone company. The cell phone maker may design its own cell phones by writing mid-level or high-level program codes into the SOC 120 for modification.
For the purpose of readily modifying the SOC 120, the SOC supplier may provide a program tool for the use of the cell phone maker. A conventional program tool is illustrated with the diagram of FIG. 2. In the first processing step 21, a first input data 210 is inputted and processed into a first output data 211. The first output data 211 is then inputted and processed in a second processing step 22 independently or along with a second input data 220 to generate a second output data 221, which is further inputted into a third processing step 23. The second output data 221 and/or a third input data 230 are processed in the third processing step 23 to generate a third output data 231, which are final program codes for SOC control and stored into a memory 25. The nodes 201, 202 and 203 shown in the diagram indicate several portal sites where the cell phone maker is allowed to arbitrarily check or edit the program codes of the program tool.
In other words, via the nodes 201, 202 and 203, partial contents of the program tool, e.g. the first output data 211, the second out data 221 and the third output data 231, are visible to the users of the program tool, which is undesired by the SOC designer. For example, the contents may disclose the details of the instruction set when the SOC is a RISC (reduced instruction set computer) with a DSP (digital signal processor) function.